visual c++ - How to set last Unused drive letter to Combobox in MFC (VC++)? -

how set last unused drive letter combobox in mfc (vc++) ? code :

tchar g_szdrvmsg[] = _t("a:\n");   int main(int argc, char* argv[]) {    ulong udrivemask = _getdrives();      if (udrivemask == 0)    {       printf( "_getdrives() failed failure code: %d\n",               getlasterror()); //so getlasterror retuns sring or char*?    }    else    {       printf("the following logical drives being used:\n");     while (udrivemask) {      if (!(udrivemask & 1))          m_objcmbdrive.addstring(g_szdrvmsg);       ++g_szdrvmsg[0];      udrivemask >>= 1;       } 

} }

m_objcmbdrive.setcursel();  

what value should pass setcursel set drive letter in descending order.

this code gives me drive drive letters being used in system. how unused 1 out ?

to select last item in combobox, can do:

m_objcmbdrive.setcursel(m_objcmbdrive.getcount() - 1); 

to fill combobox unused drive letters in descending order, use insertstring() method:

for (int = 0; < 26; ++i) {     if (!(udrivemask & 1)) {         m_objcmbdrive.insertstring(0, g_szdrvmsg);     }     ++g_szdrvmsg[0];     udrivemask >>= 1; }